The present invention relates to a unitary plastic closure mechanism for securing a container cover to a base, and more particularly to a plastic closure mechanism incorporating a living hinge construction which is integrally molded with a plastic container.
The increased use of molded plastic containers for various purposes, including use as card, letter, and document files, has led to the need for a simple, inexpensive, and reliable construction to close and lock such containers. Previous closure mechanisms have included multipiece constructions of metal, plastic, or a combination of the two. Many of these prior mechanisms required a number of assembly steps as well as the step of fastening the closure mechanism to the container.
However, all of the prior art constructions have had one or more drawbacks. Multipiece closure mechanisms required individual manufacturing operations for each component part as well as expensive and time consuming assembly operations. Moreover, when separate fastening means such as screws or pins were required, not only was an extra assembly step required, but also the stresses associated with operation of the mechanism tended to cause cracking or breakage of the plastic containers at the fastening points.
Accordingly, the need exists in the art for a reliable closure mechanism which is inexpensive to manufacture and requires no separate assembly operations.